高含H2S环境中CO2对P110套管钢氢脆腐蚀行为的影响

The Effect of CO2 on Hydrogen Embrittlement Corrosion Behaviors of Tubular Steel P110 in Acid Solution Dissolved High H2S

关键词:  套管钢  H2S/CO2  SSC  氢渗透  腐蚀产物膜

Key words:  tubular steel  H2S/CO2  SSC  hydrogen permeation  corrosion scale

摘要:

通过溶液浸泡、恒载荷硫化物应力腐蚀开裂(SSC)、电化学氢渗透等实验方法分别分析API-P110套管钢在高含50%H2S和50%CO2的酸性溶液中和在高含50%H2S酸性溶液中氢脆腐蚀行为,探讨了CO2对套管钢氢脆腐蚀行为的影响。与未经过腐蚀试样相比,在H2S与CO2共存环境中和在H2S腐蚀环境中P110套管钢的强度(抗拉强度(bσ)和屈服强度(sσ))和延伸率(δ)下降,发生晶间断裂。与单一H2S环境相比,在H2S和CO2共存环境中钢的强度和延伸率下降程度较小、脆化率小、SSC敏感性低、氢渗透速率(J)小。在不同腐蚀环境中钢的氢渗透电流密度(J)都呈现随时间(t)延长急剧增加到峰值,然后缓慢下降直到出现稳态。在高含H2S腐蚀环境中,CO2提高了腐蚀产物膜的致密性,降低了膜中FexSy含量,减少了钢的氢原子渗透量,从而降低钢的氢脆敏感性。

Abstract:

Hydrogen embrittlement behaviors of tubular steel API-P110 in the acid solution dissolved 50% H2S and 50% CO2 or 50% H2S only were investigated by immer- sion test, sulfide stress cracking corrosion (SSC) at the constant loading, and electrochemical hydrogen permeation test. Effects of CO2 on hydrogen embrittlement corrosion behavior are discussed. Compared to that of steels without being corroded, in H2S and CO2 or H2S only, the tensile strength(σb), yield strength (σs) and elongation rate at rupture(δc) of steel decline; comparing with in H2S only, the strength and elongation of steel in H2 S and CO2 decline less, embrittlement rate is low, the SSC susceptibility of steel lightens, and hydrogen permeation rate(J) decreases. In various corrosive environment, hydrogen permeation density (JH) dramatically increases to peak value as time goes on, then descend slowly until the steady state appears. In high H2 S, CO2 improves compactness of corrosion scale, and de- creases the content of FexSy in scale. Therefore, the amount of hydrogen permeation in H2 S and CO2 is more than in H2 S only, as results in the susceptibility of hydrogen embrittlement of steel decreases.